This invention relates to a vacuum frame. More particularly, this invention relates to a vacuum printing frame for reproduction purposes.
It is well known in the art to provide a vacuum frame for reproducing an original document or work of art utilizing a sensitized material. However, most of the prior art vacuum frames include a vacuum pump in direct communication with the vacuum chamber of the vacuum frame, in which the pump must be manually actuated each time the vacuum frame is used. It can be seen that the utilization of such a prior art device results in an inefficiency and time consumption which are undesirable in this field.
Still other prior art devices utilize an automatic means in which a vacuum pump is automatically activated by a switching arrangement upon a manual closing of the glass cover upon the base portion. However, these apparatuses utilize switching arrangements that are complex and expensive. Moreover, each time the apparatus is utilized, the vacuum pump must be activated in order to create a vacuum within the vacuum chamber of the frame. An example of such an apparatus can be seen in U.S. Pat. No. 3,357,335.
Other prior art devices utilize a vacuum pump and a vacuum tank to create a vacuum between two parallel spaced plates. For example, U.S. Pat. No. 3,759,613 discloses a photoplotter cassette in which a vacuum tank is disposed between the vacuum chamber of the two parallel spaced plates and a vacuum pump. Disposed between the vacuum tank and the vacuum chamber is a valve. In this manner, when the valve is manually closed, the vacuum pump creates a vacuum within the vacuum tank and when the valve is open the vacuum tank creates a vacuum within the vacuum chamber. However, in utilizing this apparatus each step must be done manually and there is no disclosure utilizing the vacuum in the tank to create a vacuum within the vacuum chamber over numerous operations.
The present apparatus is believed to solve these aforementioned problems in the art.